This invention relates to a pollution remedial composition, its manufacture, and method of using the pollution remedial composition.
Hazardous Wastes, toxic spills, contaminated water, contaminated soil, and pollutants are but a few of the environmental problems we face today all over the world. Since late 1970's, great concern was expressed over the disposal of hazardous or toxic wastes.
Common pollutants in soil and in water include asbestos, polychlorinated biphenyls ("PCB"), chlorinated hydrocarbons, petroleum products, pesticides, herbicides, and heavy metals. Most of these pollutants are man-made and have relatively long half-lives. Recent development and dissemination of such sophisticated and sensitive equipment as gas chromatographs, coupled with flame ionization and electron capture detectors, have allowed detection of pollutants with unheard of precision and accuracy.
Asbestos was used extensively prior to the 1980's to insulate structural steel and heating ducts, as a fibrous material in acoustical ceilings, in various applications on space heating and cooling units, in roofing papers, and in vinyl tiles adhesives. Asbestos can be analyzed and identified rapidly and inexpensively by microscopic analysis. Removal of the asbestos from a contaminated site is possible, but the task is invariably expensive. Further, it is never the best solution if the job is not properly done.
PGB's are widely used as insulation in electrical equipment, such as transformers and capacitors. If an electrical equipment contains PCB's, the equipment, its support platform, and the soil under and around the area most likely will contain these pollutants. The polymers are, to a certain extent, fire resistant. When they are burned, however, some toxic dioxin is formed as a by-product of the combustion, along with phosgene and hydrochloric acid. The toxic dioxin produced is the toxin reported in "Agent Orange." PCB's biodegrade very slowly. Their very low vapor pressure precludes their loss to the atmosphere. Thus, cleanup of PCB's is particularly expensive since incineration is the normal method of decontamination of removed material.
Chlorinated hydrocarbons have been widely used for at least five decades. These materials are used in paint thinners, paint strippers, degreasers, and "dry cleaning" solvents. Chlorinated hydrocarbons generally include dichloromethane, chloroform, carbon tetrachloride, dichloroethenes, and others. Carbon tetrachloride is very toxic and when burned forms phosgene and hydrochloric acid. Chlorinated hydrocarbons have relatively high vapor pressure, and their density is greater than that of water. These solvents are very likely to enter soil and groundwater. These materials enter the soil rapidly and move downward as liquid. Decontamination soil containing this class of pollutants is usually done by excavation and gas extraction. At one time, the decontamination was done by volatilization to atmosphere. Now, this old method is not considered acceptable in most areas.
Petroleum product pollutants are common in virtually every area used by man. Petroleum products include motor fuels, standard solvents, kerosene, and paint thinners. Benzene, a constituent of gasoline, is carcinogenic. The most prevalent risk today is from leaking tanks. There is usually very little opportunity for degradation deep in the soil column or in an underground water column.
Pesticides and herbicides have been in general use since the early 1940's. They were used on farm crops, for right-of-way control, for forest management, and even for decorative management in houses and gardens. Pesticides are not only toxic but degrade slowly. Cleanup of these pollutants is exceedingly expensive.
The most common heavy metal pollutants include lead, chromium, and mercury. Lead has been widely used in car batteries and paints. These heavy metals do not degrade because they are basic elements. Some, such as mercury, are, however, capable of biotransformation from inorganic to organic forms. One of the techniques to decontaminate such pollutants is adjustment of the pH. Oxidation and reduction actions are also used to decontaminate these pollutants.
Although not considered a pollutant, forest fires, oil-field fires and other fires are likewise hazardous. They are hazardous not only because of the damage they cause to the properties and materials, but also because of the gases generated by them.
For large scale decontamination of soil pollutants, one of the ways currently used is to excavate the soil, spread the soil out on a polyethylene film sheet, then allow the low-boiling hydrocarbons to be released into the air. Afterward, the soil must be taken to a hazardous waste landfill or even transported to an incinerator where the remaining pollutants are burnt. In burning this soil, gases, some toxic, are released to the air. Even after this costly procedure, the remainder still may have to be deposited into a hazardous waste landfill.
Biological treatment of wastes has also been tried. In this method, the pollutants are exposed to some microorganisms. The method will fail, however, if the annual rainfall is high and the erosion potential is not minimal. Difficulties also arise when the technique is applied in a careless manner.
It is thus clear that there is an urgent need for an effective pollution remedial composition.